I know it doesn’t look like it…but creating this table was a daunting task.  And I am still not happy with it.  I reviewed tons of online sources and they simply lack consistency.  So I went to some scientific papers and they also did not give me the confidence I was looking for.  I will get a blog post on these later.  So I visited product manufacturing sites and in one case actually telephoned the manufacturer.  So you might think that this is the ‘one list to rule them all’.  It is NOT.  Consider this table a good place to start.  But why the inconsistency?  Why the confusion?

The confusion starts with the label on the bottle.  Did you buy a refined, partially refined, virgin or extra-virgin oil?  Maybe the bottle doesn’t say any of those things. Or maybe it says light, extra light, pure, pomace, cold pressed, hot pressed, first pressed, expeller pressed or solvent extracted.  Oh, there are more examples, such as high oleic and high linoleic oils.  These terms are not just marketing hype – they describe huge differences in the way they were manufactured as well as the actual ingredients in the oils.  So a person complaining about their experience with a certain oil may have gotten confused about what they were actually using.  On top of that, testing for smoke point doesn’t really have consistent standards.  So no matter of we are comparing scientific data, user experience, or reading numerous web sites…we sometimes are not speaking the same language.  

There are plenty of specialty oils out there that look good for some purposes but may be awful for seasoning cast iron.  It can be difficult to know accurately and it leads to smoky houses, sticky pans and disappointed people.  So what should you do?  Either experiment and see what works for you or make it easy for yourself and follow some simple suggestions.  Personally, I will always suggest using a refined oil and setting the oven temperature under the smoke point.  

Under/Above the smoke point?

Let’s tackle what some of you may be thinking since it is a common point of contention.  Some users stress that your oiled pans must be heated above the smoke point of your oil in order to build carbon into the oil polymer.  Personally, this is something I do not want to do (see above – running out of a smoky house) but more importantly, I do not feel it is necessary. 

As I mentioned earlier, a pan’s seasoning only starts with the initial seasoning step.  And every time you cook with it, the seasoning will get deeper in color, thicker and more resistant.  Carbon will certainly be integrated into the seasoning over time.  Perhaps exceeding the smoke point could build a thicker polymer layer more quickly?  Maybe.  There is just nothing that makes me want to do this.  I feel anyone can create a wonderful initial seasoning with the instructions found here and it just gets better the more you use it. 

Throughout this site, I will be pointing out several variations that people use in the seasoning process (or restoration, cooking, etc).  People have opinions and experiences different than mine – and we all want to hear about them.  As I mentioned earlier – I set up a blog post on this topic so we can gather up some comments from you.  We all can learn from discussions like this! Post – Initial Seasoning

Use the table above as a guide and choose a clear, refined oil with a high smoke point for seasoning your cast iron.  Unless you are using Crisco shortening, of course.  And here is a spoiler…I highly recommend using Crisco.  And I will tell you exactly why.

Here are my top four oils:

1. Crisco Shortening
2. Canola Oil
3. Peanut Oil
4. Grapeseed Oil  

Using Crisco is easy and cooks on beautifully.  One of the greatest things about Crisco is that it is the same every time.  There is no confusion in what you are using.  It is cheap, usually available and the very little amount that you are using to cover the pans forms an extremely hard coating.  But what is it?

Crisco, was born in a Proctor and Gamble laboratory way back in 1911 from partially hydrogenated cottonseed and soybean oil.  It was formulated so it did not need refrigeration and had an extended shelf life compared to the alternatives.  Better living through chemistry!  And it was extremely popular.    

But if you are trying to eat healthy- you probably heard of partial hydrogenation.  Partially hydrogenated products create trans fats and it is generally considered to cause cardiovascular disease by both raising LDL (bad cholesterol) and lowering your HDL (good cholesterol).  The owners of Crisco (now J.M. Smucker Co. since 2002) deliberately changed the formula to use less partially hydrogenated cottonseed and soybean oils and more fully hydrogenated cottonseed oil — which contains no trans fat.

But the stigma exists and some people don’t like Crisco since it has gone through such chemical manhandling and is associated with poor health.  I do not use Crisco to bake (but truthfully, I don’t do much baking).   But if I did – I would probably not use Crisco to bake (I freely admit it – I like butter).  I do not agree with the argument that “if you would not eat Crisco…then don’t put it on your pans”.  Personally, I do not see this as being equivalent.  At all.  If you do not want to use it as a shortening in baking then I agree with you.  There are better alternatives.  But the use of it in seasoning is completely different.  The thin layer of Crisco you are putting on the pans in the initial seasoning is getting completely changed (through polymerization).  It no longer bears any resemblance to the Crisco in the tub – physically or chemically.   And I will show you below.     

Polymerization

As I said above, we want to bake on the oil into a hardened layer (called polymerization).  OK…our oven is set and we have chosen an oil that has a smoking point a fair amount above our oven temperature.  And there is no need to just squeak in below the smoke point.  Ovens have hot spots and some oven’s true temperature do not always match the what the dial says. 

Fair warning…I am not going to tell you exactly what is going on during polymerization because I do not know exactly.  It is not entirely clear what is going on during polymerization.  More specifically, there are likely many things occurring during this seemingly simple act of heating oil on iron.  The different components in the oils are breaking down at different temperatures and the monounsaturated, polyunsaturated and saturated fat molecules are linking and crosslinking to form complex chemical structures. 

Earlier we touched on some of the basic organic chemistry.  We learned that oils are made up of monounsaturated, polyunsaturated and saturated fats.  Let’s look at some examples: 

Monounsaturated fat:  Oleic acid is a very common monounsaturated fat and it looks like this:
C₈H₁₇CH=CH(CH₂)₇COOH

Polyunsaturated fat: Linoleic acid is a very common polyunsaturated fat and it looks like this:
CH₃(CH₂)₄CH=CHCH₂CH=CH(CH₂)₇COOH 

Saturated fat: Palmitic acid is a very common saturated fat and it looks like this:
CH₃(CH₂)₁₄COOH

If you remember from earlier – you can see that they are all made up of carbon, hydrogen and oxygen.  But these fatty acids are not floating around on their own.  They are usually gathered up into groups of triglycerides.  If these Fatty Acids were on their own they would be “Free Fatty Acids”, and they would be undesirable (impart a bad taste to oils).  They are also the first to start breaking down when heated. So we don’t want them.  

And as I mentioned above, a whole lot happens when heat is applied.  The chemical chains above start to break down and reform into longer chains.  And those chains crosslink with others and now you have long complex molecules that are not only long but have turns, layers and rings.  The oil layer is now hardened into a shell…a thin, translucent, water-repellent layer.  In fact, I tend to think of it more like a shellac (C₃₀H₅₀O₁₁).

This layer is not the oil we started with and we now have a complex and hardened layer that is nonstick, repels water and keeps the iron from rusting. 

And the seasoning process has only just started.  The initial seasoning creates an excellent polymer layer around your pan, protecting it from rust and making it easy to clean. The seasoning will improve every time you use it.  Will a fried egg slip out of the pan on your first try?  Maybe. Maybe not.  Be sure to see our cooking tips. 

Drying Oils

There is a current thought that one of the drying oils is a better oil to use in the seasoning process.  A drying oil is one that when left out on its own will absorb oxygen and dry on its own (like oil paints).  And people like to point out flaxseed oil as an example of a great seasoning oil since its iodine number is so high (a measure of “drying” ,or more specifically, its level of unsaturation).  Blog post coming on drying oils.  

Personally, I am not a flaxseed oil user and my reasons for not using it are more basic.  Flaxseed oil should be always refrigerated and has a short shelf life (turns rancid easily) and once it starts to go – it has a distinct fishy odor.  And just because an oil readily absorbs oxygen from the atmosphere at household temperatures does not make it a good seasoning oil.  The smoke point of unrefined flaxseed oil is 225^oF – the lowest of any oil in the table above.  You would be forced to polymerize above the smoke point – something I do not find necessary to do.  A thin coat of any of the preferred refined oils for 1 hour at 375 degrees F polymerizes into a dry and uniform layer.  It won’t matter if it was a drying oil or not. 

I said this at the beginning, and it is important enough to mention at the end.  The initial seasoning is important but NOT the most important step to getting the nonstick surface you want.  The true magic comes from using the pan and maintaining it well.